The present invention relates to provisioning for interoffice traffic in switched telephone networks, and in particular, to a system and method for provisioning dynamic high usage trunk groups between end offices in a switched telephone network.
Bearer traffic in a switched telephone network may be characterized as intraoffice traffic, interoffice traffic and interexchange traffic. Intraoffice traffic is traffic that originates and terminates in an end office. Interoffice traffic is traffic that originates in an end office and terminates in another end office in the same exchange. Interexchange traffic is traffic that originates at an end office in one exchange and terminates in an end office in another exchange. Interexchange traffic is routed through one or more tandem switches before it reaches a terminating end office.
Interoffice traffic may also be routed through a tandem switch, but where traffic volume warrants, it is much more efficient to provision direct trunk links between the end offices. These direct trunk links are referred to as high usage trunk groups. Although high usage trunk groups are less costly to provision and maintain than tandem trunk groups they do have one distinct disadvantage. Interoffice traffic volume generally fluctuates considerably, often in a substantially cyclic pattern. Peak traffic periods may be quite high, especially with the current exponential growth in demand for access to the Internet using switched telephone facilities. In order to meet customer expectations, telephone service providers must provision their high usage trunk groups to accommodate most calls during peak usage periods. Not only is such provisioning expensive, much of the high usage trunk group capacity may be idle a large part of the time. Due to the nature of switched telephone trunks, however, the idle capacity of high usage trunk groups cannot be used for other purposes. Consequently, there is a recognized need for a method and system which permits interoffice facilities to be used dynamically so that not only are facilities available to serve all calls during peak usage periods, but the facilities are available for other services during off-peak hours.
There has been considerable recent interest in using asynchronous transfer mode (ATM) backbone networks for the transfer of switched telephone traffic to increase network capacity. Several different systems for accomplishing this have been invented, including Applicant""s co-pending patent application entitled TRANSIT TRUNK SUBNETWORK filed Sep. 23, 1998, and assigned application Ser. No. 09/158,855.
A transit trunk subnetwork has several distinct advantages over switched telephone network facilities when utilized as described in the above-referenced patent application. For example, the ATM backbone resources in the network can be dynamically allocated to serve calls as required. During low usage periods, the ATM backbone resources can be used for other purposes such as data transfer to other networks. Since the transit trunk subnetwork is a multipurpose network, the cost of overhead and maintenance is distributed over a broader user base and per unit usage costs are correspondingly reduced.
Furthermore, in view of the advances in ATM backbone networks it has now been recognized that the provisioning and management of switched telephone trunks is quite expensive and contributes significantly to the operating overhead of telephone service providers. There therefore exists a need for a method of organizing switched telephone trunk facilities at the switch level that minimizes the maintenance overhead for those facilities to enable telephone service providers to remain competitive as other service offerings such as Voice Over Internet Protocol (VOIP), for example, are developed.
It is an object of the present invention to provide interoffice facilities which can be used dynamically, so that such facilities are available for interoffice calls during peak usage periods, and available for other services, such as data transport during off-peak usage periods.
It is another object of the present invention to provide interoffice facilities which are lower in cost to provision and maintain than conventional high usage trunk groups.
The present invention therefore provides an apparatus for providing dynamic high usage trunk groups between first and second end offices using switched virtual circuits (SVCs). The apparatus includes asynchronous transfer mode (ATM) facilities located between the first and second end offices, and interfaces interconnecting the first and second end offices with the ATM facilities. The first and second interfaces are adapted to convert pulse code modulated (PCM) data to ATM cells and vice versa. The first and second interfaces are also adapted to dynamically establish SVCs across the ATM facilities to serve as high usage trunk groups.
The invention further provides an apparatus for providing dynamic high usage trunk groups between first and second end offices in a switched telephone network using switched virtual circuit (SVC) connections established across asynchronous transfer mode (ATM) facilities. The apparatus includes first and second interfaces interconnecting the first and second end offices with the ATM facilities. The first and second interfaces are adapted to convert pulse code modulated (PCM) data to ATM cells and vice versa, and to establish SVC connections across the ATM facilities. The apparatus also includes a signaling controller for receiving call control messages from the end offices and for extracting call control information from the call control messages. The apparatus further includes a call manager for receiving the call control information from the signaling controller and for sending messages to the interfaces in order to dynamically control the establishment of SVCs between the first and second interfaces, in response to the call control information.
The invention also provides a method for controlling high usage trunk group capacity between first and second end offices in a telephone network having asynchronous transfer mode (ATM) facilities and first and second interfaces interconnecting the first and second end offices with the ATM facilities. The method comprises the steps of: dynamically establishing switched virtual circuits (SVCs) across said ATM facilities in response to calls originating from one of said interfaces in one of said first and second end offices and terminating in an interface in the other of said end offices.
The invention further provides an apparatus for dynamic control of trunks between first and second end offices. The apparatus includes asynchronous transfer mode (ATM) facilities located between first and second end offices, with a first interface connected to the first end office and a second interface connected to the second end office. The interfaces are adapted to convert pulse code modulated (PCM) data to ATM cells and vice versa, and are adapted to establish switched virtual circuits (SVCs) across the ATM facilities to serve as high usage trunk groups. The first and second end offices are adapted to receive trunk provisioning messages and are adapted to dynamically increase or decrease provisioning of high usage trunks in response to the trunk provisioning messages.
The invention further provides a method for dynamically controlling high usage trunk group provisioning between first and second end offices in a telephone network using asynchronous transfer mode (ATM) facilities having first and second interfaces interconnecting the first and second end offices with the ATM facilities. The method comprises the steps of: dynamically provisioning trunks between each of the first and second end offices and the interfaces; and, dynamically establishing switched virtual circuits (SVCs) from the first and second interfaces across the ATM facilities in response to the dynamic provisioning of trunks between each of the end offices.
The invention also provides a method of determining the number of SVCs required in a high usage group based on statistics captured by the call manager in response to requests for call completions between a pair of end offices. In accordance with the method, the call request statistics are analyzed at an end of a statistics capturing period and, if necessary, the number of trunks and corresponding SVCs in the high usage group between the end offices is adjusted accordingly. In practice, if at least a first predetermined number of requests for call completions between the two offices are received by the call manager, this indicates that there are too few trunks and corresponding SVCs in the high usage group because overflow calls are being xe2x80x9ctandemedxe2x80x9d through the call manager. Accordingly, the call manager formulates and sends control messages to the respective end offices, instructing the end offices to provision a specified number of additional trunks in the high usage trunk group. If the number of call requests is less than or equal to a second predetermined number, the call manager formulates and sends control messages to the respective pair of end offices instructing the end offices to remove a specified number of SVCs from the high usage trunk group. The end offices or the call manager subsequently formulate control messages which are sent to the corresponding interfaces instructing the interfaces to set up or release a corresponding number of SVCs. Thus, high usage trunk and SVC management becomes an automated centralized process which is self-governing. By tuning a high usage trunk/SVC provisioning and de-processing increment and a length of the statistics capturing period, efficient high usage groups are dynamically maintained.